Cooling air is often supplied to data centers and offices via ducts or plenums located under a raised floor. These same under-floor ducts or plenums may also be used for the passage of power and data cables, and openings are often provided in the raised floors to route these cables to the electrical equipment located above the floor. Unfortunately, these openings in the raised floor also allow cooling air to escape, which reduces the overall cooling efficiency of the data center or office. There is a need in the art for devices that can be mounted within a standard floor tile to accommodate the routing of cables while simultaneously restricting the loss of cooling air.